Generally, an element used for constituting a driving belt for a continuously variable transmission is equipped with a body portion with lateral sides thereof contacting a pulley of the continuously variable transmission, a neck portion connected to a center of an upper end of the body portion, and a head portion positioned on the neck portion. Lateral sides of the neck portion between the body portion and the head portion are concave portions for assembling the element to a pair of endless rings. The driving belt is constituted by assembling a plurality of the elements to the pair of endless rings via the concave portions.
Conventionally, the element for the continuously variable transmission is formed by punching the metal plate material. The technique related to a punching processing of the element is disclosed, for example, in Patent Document 1. In the punching processing method of the element for the continuously variable transmission disclosed in the document, a press device equipped with a forming punch which punches the metal plate material into a shape of the element, and a counter punch which descends together with the metal plate material, is used.
Thereafter, upon press forming, a constant counter load, which is an upward biasing force, is applied to the counter punch. Application of the counter load is performed by a counter unit using a disk spring. As a material of the element, a long metallic plate material having a plane portion equipped with a predetermined plate thickness, and having a pair of thinned portions via a pair of corner portions in a longitudinal direction of both side portions of a lower surface thereof, is used.
Further, Patent Document 2 discloses a general press device equipped with a processing punch and a processing die, and which implements a stamping processing or a punching processing to a general metal thin plate.